1. Field of the Invention
The present invention relates to dielectric ceramic compositions, ceramic substrates produced using the dielectric ceramic compositions, and methods for producing the ceramic substrates, and particularly, to improvements of the dielectric compositions to increase the strength of ceramic substrates.
2. Description of the Related Art
A dielectric ceramic composition is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2002-137960. According to this publication, the composition ratio of a dielectric ceramic composition that can be fired at a relatively low temperature is specified in order to increase the thermal expansion coefficient to increase the mounting reliability and to reduce dielectric loss so as to reduce transmission loss at high frequencies.
However, the dielectric ceramic composition according to Japanese Unexamined Patent Application Publication No. 2002-137960 has a problem in that a ceramic substrate produced using the composition has a low chemical resistance and is eroded when external conductive films formed on the ceramic substrate are plated. This composition also has a problem in that the ceramic substrate can be cracked or broken if the substrate is dropped or due to a temperature change, for example.